Field of the Invention
The present invention relates to a sheet conveying apparatus that is communicably connected to a post-processing apparatus and conveys a sheet to the post-processing apparatus, an image forming apparatus, an image formation system, and a post-processing system.
Description of the Related Art
Conventionally, there has been known a post-processing apparatus, such as a bookbinding apparatus, that performs post-processing, such as saddle-stitch bookbinding, case binding, and ring binding. Further, for the market of production printing, there has been proposed a bookbinding system in which a post-processing apparatus is connected to an image forming apparatus, such as a printer and a digital multifunction peripheral, to thereby seamlessly perform processing from printing to bookbinding.
In a bookbinding system including a ring binder, there has been proposed a technique for detecting a ring abnormality in a ring cartridge that stocks a plurality of rings for binding a sheet bundle, and inhibiting ring binding when the ring abnormality is detected (U.S. Pat. No. 8,132,994). Examples of the ring abnormality include an abnormality of a set state of the rings in the cartridge and an insufficient remaining amount of the same.
The post-processing apparatus, such as a bookbinding apparatus, has various functions and adjustment items, and accordingly, a user interface section of an image forming apparatus having the bookbinding apparatus connected thereto is required to be capable of setting these functions and adjustment items of the bookbinding apparatus. To display information e.g. of these functions and adjustment items of the bookbinding apparatus on the user interface section of the image forming apparatus, and execute a job, the bookbinding apparatus and the image forming apparatus are required to perform communication therebetween for various purposes.
The bookbinding apparatuses in the production printing markets tend to be manufactured in small lots of a large number of models. The image forming apparatus does not necessarily have a genuine bookbinding apparatus connected thereto. That is, the configuration of a bookbinding system which is constructed by a selected combination of an image forming apparatus and a bookbinding apparatus depends on the needs of each user. It takes a lot of time to put such a bookbinding system on the market after adapting each bookbinding apparatus to the user interface section of the image forming apparatus and making each bookbinding apparatus communicable with the image forming apparatus.
To solve this problem, there has been proposed a bookbinding system using a simple communication interface between a bookbinding apparatus and an image forming apparatus, which is simplified to such an extent that only transmission and reception of a signal indicative of delivery and reception of a sheet can be performed. In this system, a user interface is provided in each bookbinding apparatus, and configuration and adjustment of post-processing can be performed via the user interface.
Incidentally, there has been proposed a sheet conveying apparatus provided with the above-mentioned simple communication interface, for easily connecting various bookbinding apparatuses to an image forming apparatus. By connecting an image forming apparatus and a bookbinding apparatus via the sheet conveying apparatus, a bookbinding system is constructed which performs bookbinding processing without exchanging detailed information between the image forming apparatus and the bookbinding apparatus. In such a bookbinding system, the sheet conveying apparatus conveys out a sheet subjected to image formation, which is conveyed in from the image forming apparatus connected to the upstream side, to a post-processing apparatus such as the bookbinding apparatus.
The post-processing apparatus sometimes becomes incapable of continuing the bookbinding operation e.g. in a case where the amount of consumables of the bookbinding apparatus (e.g. remaining amount of ring members) becomes smaller than a predetermined amount. However, in the above-described bookbinding system in which detailed information is not exchanged between the post-processing apparatus and the image forming apparatus, even when the post-processing apparatus has become incapable of continuing the post-processing operation, such as bookbinding, it is difficult to properly stop the post-processing job. For example, even when “exhaustion of consumables” is detected, the job cannot be stopped quickly enough depending on a sheet conveying distance from a sheet feeder of the image forming apparatus to the post-processing apparatus, productivity of image formation, or the number of sheets per one copy of a finished product, which may cause e.g. a jam.
That is, after the post-processing apparatus has become incapable of continuing the post-processing operation e.g. due to exhaustion of consumables necessary for the post-processing operation or a fully-stacked state of products, the number of sheets which can be received by the post-processing apparatus without causing a jam or the like is different depending on each type of the post-processing apparatus. On the other hand, the post-processing apparatus connected to the sheet conveying apparatus is not necessarily genuine. Therefore, the sheets may be excessively supplied to the post-processing apparatus after the image forming apparatus or the sheet conveying apparatus recognizes that the post-processing apparatus has become incapable continuing the post-processing operation.